How easily can you distinguish between different DACs?

All DACs have analog stages that are different from DAC to DAC and so is the voltage output. One would bring more another would bring less... Digital domain is pretty much the same.

Yea, some high priced DACs sound like garbage so a day and night difference.    Others I have heard sound just fine.  Just spend days comparing bottom tier chip DACs and the differences are as slight as different filters.   I have yet to hear one "markedly better" but I'll keep searching.  If I had $10K to spend, it would be on speakers. If given another $10K, It would still be on speakers.  They matter and the very best of them suck compared to a $100 DAC.  I am NOT saying a $4k DAC may not sound better even on $1K speakers, but money spent on the speakers ( or the room) will make a bigger difference. 

It really ruffles feathers, but there is a point where there is nothing circuit wise to improve on after a mid-tier level. Mass market entry tier DACs are as good or better than most studio equipment the music was mastered on.  Exclusive, aesthetics, price driven placebo, ego...   If that is of value, then the market fulfills it.  

The SQ and differences in character of DACs can be profound. The rest of the system seems to determine how much of that you'll likely hear. 

One big difference for me is that ESS based DAC's seem to always be too bright sounding on my system and headphones. Both have ribbon drivers. I ended up with an R2R DAC that sounds much better to me. 

I think the best way to decide how you like any new component is to live with it for a while.  If you don't like it, it will become obvious quickly.  If it's close, you can go back and forth and compare.  Play lots of different music- see if you enjoy things you hadn't with the prior component.  This seems to be the way reviewers do it.